The Measured Energy Value of Walnuts in the Human Diet

September 16, 2013 updated by: David Baer, USDA Beltsville Human Nutrition Research Center

Macronutrient Absorption From Walnuts: The Measured Energy Value of Walnuts in the Human Diet

The objective of this study is to measure the energy value of walnuts in the human diet and study molecular mechanisms that may help explain the beneficial health effects of walnuts. The hypothesis is that there will be less metabolizable energy in walnuts due to decreased fat digestibility.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

Previous studies have demonstrated that nut consumption imparts a variety of health benefits, including reduction of cardiovascular disease and improved satiety. The aim of this study is to determine the energy value of walnuts in the human diet and to probe mechanisms by which walnuts impart health benefits. The metabolizable energy value of walnuts will be calculated based on the chemical composition and energy content of the consumed diet and excreta. This will provide a better estimate of the energy value of walnuts than simply calculating energy value based on Atwater factors. In addition to determining the energy value of walnuts, we will evaluate the effects of walnut-rich diets on plasma phytonutrient levels and on gene expression changes to determine what protective mechanisms are activated by walnut consumption.

Study Type

Interventional

Enrollment (Actual)

18

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • United States
    • Maryland
      • Beltsville, Maryland, United States, 20705
        • USDA Beltsville Human Nutrition Research Center

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

25 years to 65 years (Adult, Older Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • Age 25 to 65 years at beginning of study
  • Body mass index between 20 and 38 kg/m2
  • Fasting glucose < 126 mg/dl
  • Blood pressure < 160/100 (controlled with certain medications)
  • Fasting total blood cholesterol < 280 mg/dl
  • Fasting triglycerides < 300 mg/dl

Exclusion Criteria:

  • Presence of kidney disease, liver disease, gout, hyperthyroidism, untreated or unstable hypothyroidism, certain cancers, gastrointestinal disease, pancreatic disease, other metabolic diseases, or malabsorption syndromes
  • Women who have given birth during the previous 12 months
  • Pregnant women or women who plan to become pregnant or become pregnant during the study
  • Lactating women
  • Type 2 diabetes requiring the use of oral antidiabetic agents or insulin
  • History of bariatric or certain other surgeries related to weight control
  • Smokers or other tobacco users (during 6 months prior to the start of the study)
  • Antibiotic use during the intervention or for 3 weeks prior to any intervention period
  • History of eating disorders or other dietary patterns which are not consistent with the dietary intervention (e.g., vegetarians, very low fat diets, high protein diets)
  • Volunteers who have lost 10% of body weight within the last 12 months
  • Known (self-reported) allergy or adverse reaction to walnuts or other nuts
  • Unable or unwilling to give informed consent or communicate with study staff
  • Self-report of alcohol or substance abuse within the past 12 months and/or current acute treatment or rehabilitation program for these problems (long-term participation in Alcoholics Anonymous is not an exclusion)
  • Other medical, psychiatric, or behavioral factors that in the judgment of the Principal Investigator may interfere with study participation or the ability to follow the intervention protocol

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Allocation: Randomized
  • Interventional Model: Crossover Assignment
  • Masking: Single

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Walnut Diet first, then Control Diet
Controlled diet with 1.5 oz/d of walnuts, followed by controlled diet without walnuts.
Other: Walnut Diet
Controlled diet with 1.5 oz/d of walnuts.
Other: Control Diet
Controlled diet without walnuts.
Experimental: Control Diet first, then Walnut Diet
Controlled diet without almonds first (control), then controlled diet with 1.5 oz/d of almonds.
Other: Walnut Diet
Controlled diet with 1.5 oz/d of walnuts.
Other: Control Diet
Controlled diet without walnuts.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Metabolizable Energy
Time Frame: Each three weeks, up to 6 weeks
Metabolizable energy content will be calculated according to the methods of Novotny et al. (2012). Fat, protein, and fiber digestibility will be calculated and the effect of walnuts on nutrient digestibility will be assessed.
Each three weeks, up to 6 weeks

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Gene expression
Time Frame: At the end of each 3-week intervention period
Gene expression in whole blood will be evaluated through global gene expression using the Affymetrix platform. Changes in specific genes observed with global gene expression technology will be confirmed through reverse transcription polymerase chain reaction.
At the end of each 3-week intervention period
Biomarkers of oxidative stress/inflammation
Time Frame: End of each 3-week intervention period
Analysis of markers such as oxidized-low density lipoprotein and inflammatory markers (C-reactive protein, interleukin-1, interleukin-6, tumor necrosis factor-alpha).
End of each 3-week intervention period
Measure of walnut nutrients and metabolites
Time Frame: End of each 3-week intervention period
Blood and urine will be analyzed for appearance of walnut nutrients and their metabolites.
End of each 3-week intervention period

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

USDA Beltsville Human Nutrition Research Center

Collaborators

California Walnut Board

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start

April 1, 2013

Primary Completion (Actual)

June 1, 2013

Study Completion (Actual)

June 1, 2013

Study Registration Dates

First Submitted

April 8, 2013

First Submitted That Met QC Criteria

April 11, 2013

First Posted (Estimate)

April 16, 2013

Study Record Updates

Last Update Posted (Estimate)

September 17, 2013

Last Update Submitted That Met QC Criteria

September 16, 2013

Last Verified

September 1, 2013

More Information

Terms related to this study

Keywords

Other Study ID Numbers

  • HS43

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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